A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-energy exhaust gas flow. The high-energy exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section typically includes low and high pressure compressors, and the turbine section includes low and high pressure turbines.
Damage to one of the fan blades due to bird strikes or other debris entering the fan section are known as fan blade out events. A fan blade out event generates imbalances in the fan rotor hub that can cause further damage to the engine. Once a fan blade out event is detected, the engine is quickly shut down. The short duration of time in which the engine is shut down can exert high loads on all parts of the engine. The rate at which the engine is decelerated for a direct drive turbine engines is understood to be best when it occurs relatively slowly. In a direct drive turbine engine, the fan and the driving turbine rotate in a common direction.
A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a reduced speed such that both the turbine section and the fan section can rotate at closer to optimal speeds.
A turbine engine including gear assembly between the turbine and the fan behaves differently than a direct drive engine during fan blade out events. Accordingly, it is desirable to develop and design features that compensate for fan blade out events in turbine engines including a speed reduction device.